pub fn new_birthday_probability(n: u32) -> f64 {
    if n>= 365{
        return 1.0000;
    }
    let mut i = 0;
    let mut res = 1.0;
    while i<n{
        res *= (365.0 - i as f64)/365.0;
        i+=1;
    }
    let res = format!("{:.4}", 1.0-res).parse::<f64>().unwrap();
    res
}
